SPRINGFIELD, Mo. (AP) - Robert Purnell, a deputy sheriff in a Maryland county, drew what he thought was his Taser and pulled the trigger while chasing a man wanted for not paying $348 in child support.

The weapon he drew in October 2003 was actually his Glock firearm, and the man he hit, Frederick Henry, suffered a shattered right elbow.

Critics of the Springfield Police Department and Greene County Prosecuting Attorney Dan Patterson have protested publicly that the potential punishment for Shuck, who shot an unarmed, mentally ill man on May 9, is a slap on the wrist.

Shuck, who resigned from the force in August, was charged with a misdemeanor and appears poised to escape jail time under a proposed plea deal.

But a review by the Springfield News-Leader (http://sgfnow.co/1oElsnc ) of six previous Taser-gun mishaps by law enforcement officers in the United States found that criminal charges were filed in only one of the cases, a fatal shooting in Oakland, California, in 2009.

The cases were noted in Greene County court paperwork used to charge Shuck, as part of the prosecutor’s efforts to document how unusual it is for a police officer to confuse a gun and Taser and how doing so amounts to criminal negligence.

Still, Patterson said that the charge for Shuck can’t be directly compared to other Taser-gun incidents because the facts of each case are unique.

“The material facts in the Shuck case are set out in the probable cause statement,” Patterson said. “As applied to Missouri law, those facts support only a misdemeanor charge as the highest mental element supported by the facts is one of criminal negligence - the standard for assault in the third degree.”

Steve Ijames, a former assistant police chief in Springfield who now is a consultant on police force issues, stressed that a prosecutor has discretion on whether to file charges.

“People out there protesting, ‘Shoot a person, get a slap on the wrist,’ ” Ijames said. “If you look at the other cases, that’s not factual.”

Ijames said Patterson has been fair in how he he has handled the Shuck case.

“It’s not easy for a prosecutor who works with police day in and day out to charge a police officer,” Ijames said. “I think it speaks to his integrity.”

Shuck, 35, has offered to plead guilty to a misdemeanor charge of third-degree assault, which carries a maximum sentence of a year in jail. A proposed plea deal would leave him with no criminal record if he successfully completes two years of unsupervised probation. Shuck is scheduled to be sentenced Wednesday by Associate Judge Ron Carrier.

The proposed plea agreement also requires Shuck to never work again in a job that requires him to carry a firearm and to surrender his peace officer license.

“If you’ve been a career police officer and you’re never allowed to work in that field again, that’s a pretty significant punishment,” Ijames said.

The Taser gaffes amount to only a very small percentage of the roughly 2.2 million uses of a Taser, according to Greene County court documents.

Only six prior cases of a suspect being mistakenly shot with a handgun instead of a Taser have been documented in the United States, according to research by Ijames. Another case was in Canada.

The other United States cases include: a Sacramento, California, officer who shot a handcuffed suspect in the back seat of a police car in March 2001; a Rochester, Minnesota, police officer who shot a refugee from Sudan in September 2002; and a Madera, California, police officer who fatally shot a handcuffed suspect in 2002 arrested after a loud music complaint who was trying to kick out the window of a police car.

The remaining cases are from Kitsap County Washington, where a sheriff’s deputy shot a man who was in a tree in June 2006; and Oakland, California, where a police officer for the public transit system fatally shot a man in 2009 who was resisting being handcuffed.

Taser told law enforcement officers as early as 2001 to keep guns on their strong-hand side, usually the right side, and Tasers on the other side of their body, to avoid confusion between the two.

Shuck, the Springfield officer, carried his department-issued Glock semiautomatic on his right side and his Taser on his left side. But somehow he got the two weapons mixed up.

Shuck had to reach across his body with his right hand to draw the Taser that weighed about a third as much as the handgun.

“The best explanation that I have is that my … brain was saying Taser … but my body moved faster than my brain,” Shuck told an investigator, according to the probable cause statement filed in Greene County Circuit Court.

The man Shuck shot, Eric David Butts, 27, suffered serious intestinal injuries because of the shooting. He underwent surgery this month and is expected to recover fully.

Butts’ lawyer said he’ll seek damages against the city. The attorney, Josh Roberts, said Patterson discussed the plea deal with them before it was even presented to Shuck’s attorney.

“Mr. Butts is satisfied with the plea agreement and is pleased that officer Shuck has pled guilty and taken responsibility for this grossly negligent” action, Roberts said.